Collective States Research Articles

Deterministic Conversion from GHZ State to W State with Rydberg Superatoms

AbstractQuantum entanglement is playing an increasingly crucial role in the field of quantum information. The conversion between different types of entangled states, especially for GHZ state and W state, can greatly enhance the efficiency of quantum information processing. Here, a two‐step scheme is proposed to realize the conversion between GHZ state and W state with Rydberg superatoms, in which the collective states of superatom are used to encode quantum information. In the first step, let a single‐photon pulse pass through two cavities that trap superatoms in sequence and detect the state of photon to complete this task. In the second step, shortcuts are employed to adiabaticity based on superadiabatic technique and design appropriate Rabi frequencies for the system. The numerical simulations demonstrate that this scheme possesses a high fidelity and exhibits robustness against detrimental effects such as atomic spontaneous emission, cavity losses, fiber photon leakages and noise. Furthermore, the intricate pulses within this scheme are decomposed into a linear superposition of Gaussian pulses, enhancing experimental feasibility. Finally, the scheme is extended to deal with the scenario of multi‐superatom. This method provides a way to convert other types of entangled states.

The rediscovered unknown “small Ruijsch collection” of dry and wet anatomical specimens

Peter the Great (1672–1725) – the Russian emperor travelled through Europe during the so-called “Great Embassies” to acquire knowledge in the field of science and industrial production. In Amsterdam (Netherlands), he received as a gift from Frederik Ruijsch samples of dried and wet anatomical specimens, consisting of objects of both natural history and human origin, and currently called the “small collection”. The anatomical part of the collection consisted of 11 dry and 13 wet specimens, parts of the human body. The authors rediscovered this collection in 2016 among the exhibits of the fundamental museum of the department of normal anatomy of the Military Medical Academy (St. Petersburg, Russia). In the article we describe the current state of this historical collection, which played an important role in the acquisition of a more extensive collection by Peter the Great from Ruysch for the Kunstkamera (Museum of Anthropology and Ethnography of Peter the Great in St. Petersburg). The Kunstkamera collection is open to the general public, and as a result is well known through publications in literature. On the contrary, the so-called “small collection” was, from the moment of its arrival in Russia in 1698, in the personal possession of Peter the Great. He later divided his small collection for educational purposes between the Aptekerskii Prikaz and the medical school of Nicolaas Bidloo. Around 1800, both parts of the small collection were reunited and transferred to the Medical-Surgical Academy. Today, this collection still serves educational purposes, but is not widely available to the general public. As a result, it remains virtually unknown.

Tuning the Coherent Interaction of an Electron Qubit and a Nuclear Magnon

A central spin qubit interacting coherently with an ensemble of proximal spins can be used to engineer entangled collective states or a multiqubit register. Making full use of this many-body platform requires tuning the interaction between the central spin and its spin register. GaAs quantum dots offer a model realization of the central spin system where an electron qubit interacts with multiple ensembles of ∼104 nuclear spins. In this work, we demonstrate tuning of the interaction between the electron qubit and the nuclear many-body system in a GaAs quantum dot. The homogeneity of the GaAs system allows us to perform high-precision and isotopically selective nuclear sideband spectroscopy, which reveals the single-nucleus electronic Knight field. Together with time-resolved spectroscopy of the nuclear field, this fully characterizes the electron-nuclear interaction for control. An algorithmic feedback sequence selects the nuclear polarization precisely, which adjusts the electron-nuclear exchange interaction via the electronic g-factor anisotropy. This allows us to tune directly the activation rate of a collective nuclear excitation (magnon) and the coherence time of the electron qubit. Our method is applicable to similar central-spin systems and enables the programmable tuning of coherent interactions in the many-body regime. Published by the American Physical Society 2025

Radical youth? Israel’s educational anxiety in response to high school political protests, 1967–1973

ABSTRACT Between 1967 and 1973, Israel experienced a wave of cultural and political protest, reflecting global trends and local tensions linked to the waning dominance of the Israeli Labor Movement. These protests influenced high-school students, who organized direct and collective actions challenging state policies. This article examines the institutional response to these protests, arguing that it sparked a form of public-educational moral panic. This reaction aimed to suppress political critique by framing youth dissent as a threat to societal values, thereby deflecting attention from growing disillusionment with the Labor Movement and highlighting tensions between educational authority, political identity, and national consensus.

Broadband Acoustic Purcell Effect from Collective Bound States in the Continuum.

The Purcell effect significantly improves the performance of various emission devices but is typically constrained by a narrow operational bandwidth due to inherent resonant mechanisms. This study achieves broadband acoustic Purcell effect, substantially boosting sound emission by exploring collective quasibound states in the continuum (QBICs). A six-cavity coupled system supporting five QBICs is introduced, wherein all of the QBICs interact strongly with an acoustic source. This system takes advantage of the high quality factors and the strong mode responses of the collective QBICs, leading to a substantial enhancement of the local density of states. Consequently, a considerable increase in sound emission is realized across the frequency range of 625-900 Hz. These findings provide insights into the physical mechanisms driving the broadband Purcell effect in resonant systems and open up promising avenues for the development of advanced acoustic emissiondevices.

Simple robot swarm with magnetic coupling connections can collaboratively accomplish collective tasks

Abstract The use of robotic swarms to study the properties of active matter is a common experimental approach. In such studies, robots are often required to possess capabilities in computation, storage, perception, and two-dimensional movement to execute predefined rules. Under these rules, the swarm can accomplish complex tasks, exhibit rich collective states, or demonstrate intriguing phase transition phenomena. However, this study demonstrates how a swarm of spin robots, which only respond to simple ambient light intensity, can be constructed into a collective system capable of performing practical swarm tasks such as phototactic motion, controllable folding, and object transport through weak coupling interactions between individuals. Furthermore, it is proven that this swarm exhibits strong system fault tolerance. This research aims to demonstrate that, beyond the common design of sophisticated individuals and excellent inter-individual interaction rules, appropriate structural and coupling designs can enable individuals without computational capabilities to generate complex collective behaviors and accomplish diverse swarm tasks through cooperation. This provides a research direction for experimental studies of active matter using robotic systems.

Sleep pressure accumulates in a voltage-gated lipid peroxidation memory.

Voltage-gated potassium (KV) channels contain cytoplasmically exposed β-subunits1-5 whose aldo-keto reductase activity6-8 is required for the homeostatic regulation of sleep9. Here we show that Hyperkinetic, the β-subunit of the KV1 channel Shaker in Drosophila7, forms a dynamic lipid peroxidation memory. Information is stored in the oxidation state of Hyperkinetic's nicotinamide adenine dinucleotide phosphate (NADPH) cofactor, which changes when lipid-derived carbonyls10-13, such as 4-oxo-2-nonenal or an endogenous analogue generated by illuminating a membrane-bound photosensitizer9,14, abstract an electron pair. NADP+ remains locked in the active site of KVβ until membrane depolarization permits its release and replacement with NADPH. Sleep-inducing neurons15-17 use this voltage-gated oxidoreductase cycle to encode their recent lipid peroxidation history in the collective binary states of their KVβ subunits; this biochemical memory influences-and is erased by-spike discharges driving sleep. The presence of a lipid peroxidation sensor at the core of homeostatic sleep control16,17 suggests that sleep protects neuronal membranes against oxidative damage. Indeed, brain phospholipids are depleted of vulnerable polyunsaturated fatty acyl chains after enforced waking, and slowing the removal of their carbonylic breakdown products increases the demand for sleep.

Collective Magnetism of Spin Coronoid via On-Surface Synthesis.

Polyradicals obtained from open-shell coronoids hold promise for applications in spintronics and quantum technologies due to the strong interactions between spins in fully fused cyclic systems. Coronoid synthesis has long been considered difficult due to the cyclization of nanographene. It becomes an immense challenge to synthesize open-shell coronoids since radicals appear only when the macrocycle size exceeds a critical value. Here we present an open-shell coronoid with six radicals achieved through an on-surface synthesis. This spin coronoid displays a collective spin state arising from both the nearest-neighbor exchange interaction and the next-nearest-neighbor exchange interaction of six unpaired π electrons along the conjugation pathways. The characterization of the spin excitation from the ground state to the excited state was carried out by using inelastic electron tunneling spectroscopy. Additionally, we show that the spin coronoid can be utilized as a nanoscale platform to achieve short antiferromagnetic spin-1/2 Heisenberg chains through tip manipulation. Our findings present a design strategy for creating coronoids with polyradicals, which could provide inspiration for fabrication of open-shell coronoid or cyclic spintronic systems.

Study of Octupole States in 150 Sm and 158 Gd Nuclei Within Sdf-Interacting Boson Model (Sdf-IBM-1) Framework

The collective octupole states found in 150,152Sm and 148,150Gd isotopes are explained inside the structure of the sdf-interacting boson model-1 (sdf-IBM1). The specifications of the IBM Hamiltonian are fitted with the experimental energy levels. By diagonalizing the IBM Hamiltonian, For positive as well as negative parity states, excitation energies and electric transition rates can be obtained. We then compare these resulting spectroscopic features with the currently available experimental data. Furthermore, the framework of excited 0+states is investigated along with its relationship to double octupole phonons. The sdf-IBM-1 model demonstrates a high level of accuracy in portraying the observed trends in low-energy quadrupole states.

Bifurcations and collective states of Kuramoto oscillators with higher-order interactions and rotational symmetry breaking.

We study a network of identical Kuramoto oscillators with higher-order interactions that also break the rotational symmetry of the system. To gain analytical insights into this model, we use the Watanabe-Strogatz Ansatz, which allows us to reduce the dimensionality of the original system of equations. The study of stability and bifurcations of the reduced system reveals a codimension two Bogdanov-Takens bifurcation and several other associated bifurcations. Such analysis is corroborated by numerical simulations of the associated Kuramoto system, which, in turn, unveils a variety of collective behaviors such as synchronized motion, oscillation death, chimeras, incoherent states, and traveling waves. Importantly, this system displays a case where alternating chimeras emerge in an indistinguishable single population of oscillators, which may offer insights into the unihemispheric slow-wave sleep phenomenon observed in mammals and birds.

Multistable Synaptic Plasticity Induces Memory Effects and Cohabitation of Chimera and Bump States in Leaky Integrate-and-Fire Networks.

Chimera states and bump states are collective synchronization phenomena observed independently (in different parameter regions) in networks of coupled nonlinear oscillators. And while chimera states are characterized by coexistence of coherent and incoherent domains, bump states consist of alternating active and inactive domains. The idea of multistable plasticity in the network connections originates from brain dynamics where the strength of the synapses (axons) connecting the network nodes (neurons) may change dynamically in time; when reaching the steady state the network connections may be found in one of many possible values depending on various factors, such as local connectivity, influence of neighboring cells etc. The sign of the link weights is also a significant factor in the network dynamics: positive weights are characterized as excitatory connections and negative ones as inhibitory. In the present study we consider the simplest case of bistable plasticity, where the link dynamics has only two fixed points. During the system/network integration, the link weights change and as a consequence the network organizes in excitatory or inhibitory domains characterized by different synaptic strengths. We specifically explore the influence of bistable plasticity on collective synchronization states and we numerically demonstrate that the dynamics of the linking may, under special conditions, give rise to co-existence of bump-like and chimera-like states simultaneously in the network. In the case of bump and chimera co-existence, confinement effects appear: the different domains stay localized and do not travel around the network. Memory effects are also reported in the sense that the final spatial arrangement of the coupling strengths reflects some of the local properties of the initial link distribution. For the quantification of the system's spatial and temporal features, the global and local entropy functions are employed as measures of the network organization, while the average firing rates account for the network evolution and dynamics. In particular, the spatial minima of the local entropy designate the transition points between domains of different synaptic weights in the hybrid states, while the number of minima corresponds to the number of different domains. In addition, the entropy deviations signify the presence of chimera-like or bump-like states in the network.

On-surface synthesis of Heisenberg spin-1/2 antiferromagnetic molecular chains.

Magnetic exchange interactions between localized spins in π-electron magnetism of carbon-based nanostructures have attracted tremendous interest due to their great potential for nano spintronics. Unique many-body quantum characteristics, such as gaped excitations, strong spin entanglement, and fractionalized excitations, have been demonstrated, but the spin-1/2 Heisenberg model with a single antiferromagnetic coupling J value remained unexplored. Here, we realized the entangled antiferromagnetic quantum spin-1/2 Heisenberg model with diazahexabenzocoronene oligomers (up to 7 units) on Au(111). Extensive low-temperature scanning tunneling microscopy/spectroscopy measurements and density functional theory and many-body calculations show that even-numbered spin chains host a collective state with gapped excitations, while odd-numbered chains feature a Kondo excitation. We found that a given antiferromagnetic coupling J value between first neighbors in the entangled quantum states is responsible for the quantum phenomena, strongly relating to their parities of the chain. The tunable molecular building blocks act as an ideal platform for the experimental realization of topological spin lattices.

Collective States of α-Sexithiophene Chains Inside Boron Nitride Nanotubes.

The optical excitation of close-by molecules can couple into collective states giving rise to phenomena such as ultrafast radiative decay and superradiance. Particularly intriguing are one-dimensional molecular chains that form inside nanotube templates, where the tubes align molecules into single- and multifile chains. The resulting collective excitations have strong fluorescence and shifted emission/absorption energies compared to the molecular monomer. We study the optical properties of α-sexithiophene chains inside boron nitride nanotubes by combining fluorescence with far- and near-field absorption spectroscopy. The inner nanotube diameter determines the number of encapsulated molecular chains. A single chain of α-sexithiophene molecules has an optical absorption and emission spectrum that is red-shifted by almost 300 meV compared to the monomer emission, which is much larger than expected from dipole-dipole coupling. For two or more parallel chains, the collective state splits into excitation and emission channels with a Stokes shift of 200 meV due to the chain-chain interaction. Our study emphasizes the formation of a delocalized collective state through Coulomb coupling of the molecular transition moments in one-dimensional molecular lattices. They show a remarkable tunability in the transition energy, which makes encapsulated molecules promising candidates for components in future optoelectronic devices and for analytic spectroscopy.

Higgs boson in condensed matter system

Abstract We show that Higgs amplitude mode is possible only when a collective boson state (Higgs state) starts to exist at the onset of condensation from its previous non-collective state in the high-temperature phase before the system undergoes a phase transition to the low-temperature broken symmetry condensed phase. Thus, Higgs boson can exist not only as an excitation mode but as a physical particle. Such phase transition is a first order transition from superconductor (superfluid) to insulator which is described by the Ginzburg-Landau (GL) free energy of second-order-transition type augmented with the Higgs boson state and the entropy term of the insulator phase. Higgs boson excitation is a collective excitation of non-condensed collective boson from the condensate which makes a collective amplitude oscillation with the remaining condensate. Therefore, Higgs mode energy in the long-wavelength limit has the same magnitude as one boson condensation-resolving energy. The experimental observations of Higgs modes in charge density wave superconductor NbSe3 and in disordered superconductor films NbN and InO near the superconductor-to-insulator quantum phase transition are in good accord with the present phenomenological Higgs boson theory. Especially the dynamical conductivity of the latter strongly disordered superconductors provides the evidence that Higgs mode energy is the condensation-resolving energy of one boson.

Fractional magnetic charges and channeling of Faraday lines by disclinations in artificial spin ice

We have studied the magnetic moments of artificial spin ice arrays of nanomagnets in both undistorted square arrays and in arrays with a topological defect induced by a single disclination. We confirm that the disclination induces global, macroscopic changes in the low-energy collective states of the nanomagnet moment configuration. Specifically, the disclination leads to Faraday lines of effective magnetic flux that run from the center all the way to the edge of the arrays. Moreover, the geometric deformation, induced by the topological defect, curves the geometry such that these Faraday lines are channeled preferentially by the arrays' curved geometry. Our results demonstrate how the intentional combination of topology and geometry can be designed to control magnetic charges and the flow of local magnetization and thus manipulate associated collective excitations.

Multiscale Physics of Atomic Nuclei from First Principles

Atomic nuclei exhibit multiple energy scales ranging from hundreds of MeV in binding energies to fractions of an MeV for low-lying collective excitations. As the limits of nuclear binding are approached near the neutron and proton drip lines, traditional shell structure starts to melt with an onset of deformation and an emergence of coexisting shapes. It is a long-standing challenge to describe this multiscale physics starting from nuclear forces with roots in quantum chromodynamics. Here, we achieve this within a unified and nonperturbative quantum many-body framework that captures both short- and long-range correlations starting from modern nucleon-nucleon and three-nucleon forces from chiral effective field theory. The short-range (dynamic) correlations which account for the bulk of the binding energy are included within a symmetry-breaking framework, while long-range (static) correlations (and fine details about the collective structure) are included by employing symmetry projection techniques. Our calculations accurately reproduce—within theoretical error bars—available experimental data for low-lying collective states and the electromagnetic quadrupole transitions in Ne20−30. In addition, we reveal coexisting spherical and deformed shapes in Ne30, which indicates the breakdown of the magic neutron number N=20 as the key nucleus O28 is approached, and we predict that the drip line nuclei Ne32,34 are strongly deformed and collective. By developing reduced-order models for symmetry-projected states, we perform a global sensitivity analysis and find that the subleading singlet S-wave contact and a pion-nucleon coupling strongly impact nuclear deformation in chiral effective field theory. The techniques developed in this work clarify how microscopic nuclear forces generate the multiscale physics of nuclei spanning collective phenomena as well as short-range correlations and allow one to capture emergent and dynamical phenomena in finite fermion systems such as atom clusters, molecules, and atomic nuclei. Published by the American Physical Society 2025

Emergent Metric-Like States of Active Particles with Metric-Free Polar Alignment.

We study a model of self-propelled particles interacting with their k nearest neighbors through polar alignment. By exploring its phase space as a function of two nondimensional parameters (alignment strength g and Péclet number Pe), we identify two distinct order-disorder transitions. One occurs at a low critical g value independent of Pe, has no significant density-order coupling, and is consistent with the transition previously predicted by the mean-field approach. Up to the system sizes studied, it appears continuous. The other is discontinuous, depends on a combined control parameter involving Pe and g that controls the alignment strength, and results from the formation of small, dense, highly persistent clusters of particles that follow metric-like dynamics. These dense clusters form at a critical value of the combined control parameter Pe/g^{α}, with α≈1.5, which appears to be valid for different alignment-based models. Our study shows that models of active particles with metric-free interactions can produce characteristic length scales and self-organize into metric-like collective states that undergo metric-like transitions.

Collective and non-collective states in

The high spin states of 136Ce (Z = 58) were investigated via 124Sn(16O, 4n)136Ce fusion evaporation reaction at MeV. The γ-γ coincidence technique is used for placing the γ-transitions in the level scheme. The spin and parity of the levels have been assigned on the basis of results of the angular correlation and linear polarisation measurements, respectively. The bands based on the yrast 10+ isomeric state and the non-yrast 10+ state have been established. The structures of these bands are also compared with the band structures of the neighbouring nuclei.

BPS2025 - Changes in collective behavior, organization, and state of human induced pluripotent stem cell-derived endothelial cells exposed to shear stress revealed by 3D microscopy and quantitative image analysis

BPS2025 - Changes in collective behavior, organization, and state of human induced pluripotent stem cell-derived endothelial cells exposed to shear stress revealed by 3D microscopy and quantitative image analysis

Effects of coupling range on the dynamics of swarmalators.

We study a variant of the one-dimensional swarmalator model where the units' interactions have a controllable length scale or range. We tune the model from the long-range regime, which is well studied, into the short-range regime, which is insufficiently studied, and find diverse collective states: sync dots, where the swarmalators arrange themselves into k>1 delta points of perfect synchrony; q-waves, where the swarmalators form spatiotemporal waves with winding number q>1; and an active state where unsteady oscillations are found. We present the phase diagram and derive most of the threshold boundaries analytically. These states may be observable in real-world swarmalator systems with low-range coupling, such as biological microswimmers or active colloids.